A novel forced separation method for the preparation of paraffin with excellent phase changes

Abstract

A novel forced separation method based on driving force vacuum sweating was used to prepare high melting point paraffin with high phase-change enthalpies. The effects of the vacuum pressure and final separation temperature on the forced separation of the paraffin components were investigated. The research results showed that the optimal vacuum pressure for forced separation was 80.0 kPa. The performance of forced separation was improved with the increase in the final temperature. Increasing the final temperature increased the driving force of the separation of solid-state components and liquid components during sweating, which improved the product yield, shortened the production cycle, and reduced the oil content. The phase changes exhibited by the separation products were tested at 70 °C under optimal conditions. The raw materials and forced separation products were analyzed through Fourier transform infrared spectroscopy analysis (FT-IR), gas chromatography analysis (GC), differential scanning calorimetry analysis (DSC), and X-ray diffraction analysis (XRD). The results of these analyses showed that as the forced separation temperature was increased, the carbon atom number distribution range of the products narrowed, and the content of n-paraffin was drastically improved. The content of n-paraffin in the final fraction obtained through the forced separation of paraffin was 89.8% with a phase-transition temperature of 69.74 °C and a phase-transition enthalpy of 214.71 J g⁻¹. A significant solid–solid phase transition peak was observed in the final fraction obtained through the forced separation of paraffin, which verified that paraffin was an excellent phase-change material for energy storage.